Arthritis is a degenerative condition which, when affecting the weight bearing joints such as the hip and knee joints, results in pain and hampered mobility. Arthritis may affect all joints. Degradation of articular and meniscal cartilage may result in damage to the surfaces separated by the cartilage and correspondingly to pain. Ageing is a primary cause of the degradation of the cartilage. The degradation may also result from, for example, congenital predisposition or trauma, such as repeated articulation of the joint.
Arthritis has been treated traditionally with physiotherapy and more invasive treatments such as orthopaedic surgery and the introduction of artificial joint components. Non-steroidal anti-inflammatory agents have been used with some success but these agents may counterproductively hamper proteoglycan synthesis in collagen and cartilage as well as have undesirable side effects. Cortisone injections also weaken articular cartilage with time.
Soft compliant materials used to replace the cartilage have been developed to absorb the load on the joint and to distribute the load evenly. U.S. Pat. No. 4,344,193 discloses silicone rubber as a prosthetic device. One difficulty with these devices is securing the devices in place and various anchoring systems have been developed (U.S. Pat. No. 5,171,322; U.S. Pat. No. 4,502,161; U.S. Pat. No. 4,919,667).
Other prosthetic devices, such as in U.S. Pat. No. 5,344,459, are inflatable. The Macintosh knee is a hard prosthetic which is painful to use.
WO 00/78356 discloses an injectable composition for promoting bone and/or cartilage growth comprising hyaluronic acid cross-linked to sulfated polysaccharides.
WO 96/25129 discloses a prosthesis for joints in hands and feet comprising a biocompatible material such as a mixture of biocompatible resin and plastics. Specific materials mentioned include polymethyl methacrylate polymer. The prosthesis is implanted into the joint.
WO 00/59411 discloses a surgically implanted knee prosthesis wherein the load distribution device is constructed of material comprising a thermoset polymer or thermoplastic polymer.
Hyaluronates and hyaluronic acids have been used for prosthetics and administered by injection into the intra-articular cavity of knees for the long-term relief of pain and improvement on the function of the knee joint. It has adequate viscosity and elasticity but has been prone to sheering due to mechanical stress and is biodegradable and has faced resorption problems.
There is the need in the art for additional materials for use as an artificial cartilage such as in weight-bearing joints. The present invention is directed to a material and prosthetic device for use in the treatment of arthritis and to supplement or replace cartilage.